Coordination of Upper Extremity and Center of Mass Trajectory During Basketball Shots from Varying Distances

Casey Wiens1, Jill L. McNitt-Gray1,2


1 Department of Biological Sciences, University of Southern California
2 Department of Biomedical Engineering, University of Southern California

Introduction

  • In the course of play, basketball shots are taken from varying distances from hoop.
  • A change in shot distance affects the max angular velocity (Nakano, Fukashiro, and Yoshioka 2018) and timing of max upper extremity joint angular velocities (Podmenik et al. 2017; Miller and Bartlett 1993) relative to ball release.
  • By releasing the ball earlier relative to center of mass (CM) trajectory apex, the CM vertical velocity’s contribution to the ball vertical velocity is increased (Wiens and McNitt-Gray 2020). The timing between ball release and CM trajectory apex increases with increase in shot distance (Wiens and McNitt-Gray 2020).
  • Do individuals control the timing of the upper extremity shot initiation relative to the CM trajectory at varying distances?

Hypothesis

  • Upper extremity shot initiation would occur earlier relative to CM trajectory apex with increase in shot distance

Experimental Design

  • Participants
    • 7 recreational players (4 female; college-aged; >10 years experience)
  • Experimental Task
    • Received chest pass from person under hoop
    • Minimum 10 attempts at three distances
      • Long: 6.02 m (high school three-point line)
      • Medium: 4.57 m (free throw)
      • Short: < 2.5m

Data Collection

  • Motion capture
    • Video of ball motion (Panasonic, 120Hz)
    • Wearable inertial measurement units of upper extremity (APDM, 120Hz)
  • Force measurements
    • Two portable force plates (Kistler, 1200Hz)

Data Analysis

  • Center of mass velocity
    • Net impulse = change in momentum (using force measurements)
  • Ball release velocity
    • Projectile motion equations
  • Time of apex of center of mass trajectory
    • Projectile motion equations
  • Time of upper extremity shot initiation: earliest event of following:
    • Earliest event between: shoulder flexion or elbow extension
  • Within-participant differences between shot distances
    • Multiple comparisons on difference scores
    • p-values adjusted using Benjamini-Hochberg method (Wilcox 2017)

Results

  • Upper extremity shot initiation occurred significantly earlier relative to CM trajectory apex with increase in shot distance for all 7 participants.
  • Ball vertical velocity at release significantly increased with an increase in shot distance

Discussion

  • Upper extremity shot initiation was found to occur earlier relative to CM trajectory apex with increase in shot distance
  • These results are consistent with previous research indicating shot distance affects timing of upper extremity motion (Nakano, Fukashiro, and Yoshioka 2018; Podmenik et al. 2017; Miller and Bartlett 1993)
  • Initiating the upper arm shooting motion earlier relative to CM apex may be an attempt to take advantage of the CM vertical velocity at ball release (Wiens and McNitt-Gray 2020)
  • Changes in the timing of upper extremity shot initiation in relation to the CM trajectory apex were associated with differences in ball vertical velocity at release
  • Timing of upper body shooting motion relative to whole body motion may affect ball release angle, subsequently affecting performance outcomes

References

Miller, Stuart, and Roger M. Bartlett. 1993. “The effects of increased shooting distance in the basketball jump shot.” Journal of Sports Sciences 11 (4): 285–93. https://doi.org/10.1080/02640419308729998.

Nakano, Nobuyasu, Senshi Fukashiro, and Shinsuke Yoshioka. 2018. “The effect of increased shooting distance on energy flow in basketball jump shot.” Sports Biomechanics 3141: 1–16. https://doi.org/10.1080/14763141.2018.1480728.

Podmenik, Nadja, Matej Supej, Milan Čoh, and Frane Erčulj. 2017. “The effect of shooting range on the dynamics of limbs angular velocities of the basketball shot.” Kinesiology 49 (1): 92–100. https://doi.org/10.26582/k.49.1.4.

Wiens, Casey, and Jill L. McNitt-Gray. 2020. “The contribution of body center of mass velocity to basketball ball release velocity across shot distances.” In Proceedings of the 38th International Society of Biomechanics in Sports.

Wilcox, Rand. 2017. Modern Statistics for the Social and Behavioral Sciences. Second Edi. Chapman; Hall/CRC. https://doi.org/10.1201/9781315154480.